Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known foil principles and transmit the kinetic energy through rotational energy to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The tower of a wind turbine is typically constructed from a plurality of tower cans or segments. Each tower segment generally comprises a steel plate that has been rolled and welded at the ends to form a circular shape. The circular shaped tower segments may then be stacked one on top of the other to form a hollow tower structure. Additionally, to provide access to the interior of the hollow tower structure, a door is typically formed in one or more of the lower tower segments.
A number of the control components and cabinets (e.g., converter panels) are generally housed in the turbine down tower area. These components generate a significant amount of heat, and it has been the conventional practice to provide a louver and filter in the tower door to introduce fresh air into this down tower area. A problem exists, however, in that the louvers have a limited cross-sectional area to the flow of air and the filters become quickly clogged (particularly in environments with heavy air particulate concentrations, such as a desert of other sandy location) and block the flow of fresh air.
U.S. Pat. Publication No. 2010/0308596 describes a wind tower door assembly wherein one or more air passage openings are provided above and below the door opening, which is framed by a door frame. An air conduit within the tower is connected to the air passage opening and includes a ventilator fan for drawing air into the tower through the opening and conduit. An air discharge passage is located in the tower wall opposite from the air passage openings.
U.S. Pat. No. 8,227,932 discloses a wind tower structure wherein a concave space is defined in the tower at the location of the tower door by a partition wall disposed around the door opening. A heat exchanger is disposed in the lower portion of the concave space and circulates a cooling medium flow to components within the tower. An outside air-circulation path is established within the concave space whereby outside air is drawn through the heat exchanger, rises in the concave space, and is discharged into the atmosphere in an upper portion of the concave space.
U.S. Pat. Publication No. 2013/00009405 describes a wind tower structure wherein a tower opening is provided for introducing air into the tower. A cylindrical portion extends from the tower opening into the tower. All or a portion of the peripheral surface of the cylindrical portion includes pressure loss elements, such as louvers, for delivery of the outside air.
The above systems are relatively complicated in that they require air handling equipment and/or substantial modifications to a generally tubular tower segment that defines the down tower area incorporating the tower door, and would be relatively expensive and prohibitive as retrofit systems. Accordingly, the industry would benefit from an improved system for introducing fresh air to the down tower area of a wind turbine tower that is relatively inexpensive and easily retrofitted to existing tower structures.